Cornea is a transparent membrane located at the front of the eyeball wall, occupying about the first ⅙ of the fiber wall. Cornea takes a circular shape when viewed from behind and a transverse oval shape when viewed from the front. Cornea is the transparent part located at the most front part of the eyeball, and covers the iris, the pupil, and the anterior chamber. It provides most of the refractive power to the eyeball and facilitates correct focus of light on the retina together with the refractive power of the crystalline lens.
Meanwhile, corneal blindness due to loss of corneal transparency is a main cause of vision loss, only second to vision loss caused by cataract. Ocular trauma and corneal ulcers cause blindness to 1.5-2 million people each year. The only effective treatment for this kind of blindness is human corneal transplantation (also called “keratoplasty”).
Currently, there is a huge gap between the demand and supply of cornea material in the market. Under the circumstances that allogenic cornea is so lacking and the situation is difficult to change in the short term, people have made various efforts to develop alternative new materials to address the problem of cornea shortage.
New materials that have been reported and verified include mainly biological materials and heterogenetic corneal materials. According to the prior reports, the biomaterials have unsatisfactory tissue compatibility and cannot be used in large scale. In comparison, the heterogenetic corneal materials have broader application prospects. Current technologies focus on removing cells in heterogenetic cornea by use of a protease (trypsin) or phospholipase A2 and other chemical means.
The problem is that these enzymes also have an impact on collagen structure, and thus cause a certain degree of inhibition on the growth of corneal cells after transplantation. Prior literature also indicated a major problem in heterogenetic corneal materials, i.e., graft opacification in the early post-transplantation stage. Therefore, there is still large room for the optimization of the specific treatment methods and preparation methods above.